1. Field of the Invention
The present invention is directed to an arrangement or device for optical transmission of communications. The device or system includes at least one light transmitter with an associate light receiver which is assigned to the transmitter and which includes a light gathering body composed of a material having an index of refraction greater and 1.
2. Prior Art
An arrangement or system for optical transmission of communications, which system or arrangement comprises at least one light transmitter and a light receiver which is assigned to the light transmitter and which includes a light gathering body composed of a material having an index of refraction greater than 1, are known and disclosed in German Auslegeschrift No. 22 57 999 and in an article by Hans-Joachim Griese, Radio Mentor, Vol. 42 (1976), No. 11, pgs. 440-442.
Optical signal transmission is used in particular when large quantities of information are to be transmitted by wireless means over a relatively short distance in particular within the limits of an enclosed space. In contrast to electromagnetic radiation, which has wavelengths which are usually found in communication technology, light waves do not, in fact, penetrate through walls and are superior to ultrasonic waves in that they permit higher carrier frequencies and thus, wider band modulations. In addition, light waves are free of disturbing spatial interferences and also cannot be influenced by rattle noises. In spite of these favorable properties, light transmission systems have only been put into practice in a few cases as relatively high power transmitters having a viable degree of efficiency are, in fact, available within the infrared range although one is still confined to small receiver surfaces and must frequently accept a high alien or ambient light component.
For many years now the technical worlds has worked intensively towards increasing the light signal and the signal-to-noise ratio by development of suitable "antenna". As a rule, the concern has been to improve the specific optics such as collector lenses, parabolic reflectors or funnels and low pass filters ("cut-on filters"). It is obvious that the elements of this kind render the transmission device extremely elaborate. In addition to being extremely elaborate, the aforementioned receiver optics will increase the directional effect and necessitate additional provisions such as disclosed in U.S. Pat. No. 3,937,949, which is based on the same priority document as German Offenlegungsschrift No. 2 327 748. Furthermore, when the ambient or surrounding light has a relatively long-wave component and the receiver responds in this range, low-pass filters fundamentally have only a limited efficiency. For example, when using a transmitting diode, the receiver is a Si-photo-diode, and an incandescent light environment will reduce the efficiency of the system or arrangement.